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A Vebe Floorcoverings poupa milhares com controladores de frequência |
Os processos industriais consomem normalmente bastante energia, pelo que a utilização de controlos inteligentes de motores pode proporcionar uma vantagem decisiva em termos competitivos. O fabricante de carpetes Vebe Floorcoverings b.v., de Genemuiden, equipou os motores de ventilação de uma linha de secagem de grandes dimensões com controladores de frequência, reduzindo, assim, de imediato, uma grande parcela dos custos com electricidade. E não é tudo.
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Optimisation of drying process control
Genemuiden is literally and figuratively the home of the Dutch carpet industry. Sisal and coir matting were produced here before the war. The local industrial estate is now a showcase of well-known and less familiar suppliers of different kinds of floor coverings.
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One of the largest employers in the region is Vebe Floorcoverings, one of the largest producers of needleloom carpeting in the world. In the production of needle loom carpeting synthetic fibres are rolled into thin layers, which are then bonded together by a process in which needles are punched through the fibres, creating a strong structure. Finally a latex backing is applied. The latex is applied in fluid form and then dried with hot air. The process of heating the air, and more particularly the circulation of air with the aid of fans, requires a lot of energy, so it is the perfect production stage in which to introduce savings. Energy is a significant cost factor, and saving energy is not only good for the business but also for the environment.
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Comparative tests
In 1996 the carpet industry entered into an energy agreement with the government with the object of cutting energy consumption by twenty percent by the year 2000. Vebe has now more than met the target, largely through the use of frequency controllers. "In the mid-nineties we equipped the motors of some of the extractors in the chimneys with Omron frequency controllers," relates Marcel Potters, Manager of Backing in Vebe's Needleloom carpeting production. "We rapidly achieved a sixty percent saving in electricity, and that led to the idea of putting frequency controllers in the production lines too." In a number of tests Omron outperformed the competition by a few percentage points. Now we're already into differences that add up to tens of thousands of guilders over the year. In addition, the separate controls saved a further 1.7% in energy compared with the block controls. "The solid performance of the Omron controllers is due to the in-built intelligence, which automatically takes account of the load on the motor. For this reason Vebe opted for Omron and the separate regulation of each motor. "Block controls require less investment, but any advantage is quickly dissipated by the lack of the extra saving," says Marcel Potters. "On top of that, your are running a greater risk, because if one controller breaks down then four motors are out of action, and the whole production line stops. That costs many times the price of the controllers. So we decided to equip all 132 motors in the backing process with Omron frequency controllers."
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Second phase
They started to install the controllers in the course of 1999. They discovered that the supply frequency of the motors could be reduced from 50 to 45 Hz without any problems, which produced an immediate saving of 25 to 30 percent. "Following installation we entered the second phase, in which we linked the controllers via a network to two PLCs with touch screens. We programmed monitoring software into these, which we can use to switch and adjust each motor individually. That can be worthwhile, because not every kind of carpet needs the same amount of drying. Sometimes you can set the fans to run at 40 Hz. This enabled us to save a further 10 percent, which is more than a third compared to the old system. And note these are minimum figures. For some products the savings are as much as 65 percent!" With this more effective ventilation system the gas consumption of the burners could also be reduced by 30 percent. "Our production increases by about 20 percent per year," says Marcel Potters. With the volume of this year's output we will save more than a hundred thousand guilders in fuel consumption."
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Do it yourself
Vebe decided to install the frequency controllers itself and also to write its own software for the PLCs. "Doing it yourself is important to enable you to react quickly to any breakdowns and also offers more opportunities for further development of the operating software," says Freddy Bolt of Vebe's electrical service. He attended a short basic course at Omron and received a day's instruction in the communication protocols. That proved sufficient. "I'm not a professional programmer, but the Syswin development software is very user-friendly. Also, I had direct access to the Omron help desk. The programming went really quickly. The second PLC has twice the functionality of the first, but the programming took half the time. The knowledge we are building up in this way is useful for other applications, too. For example we have now put a PLC on the machine that rolls the carpet up and cuts it to length. The length measurement is much more accurate now. We produce thousands of kilometers per year and exact measurement can save us tens of thousands of guilders."
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